Conventional diapers are made in a flat condition. The shape of such diapers is either a rectangular or hourglass. The hourglass shape is of course preferred because it provides less bulk between the legs of the baby thus facilitating a more comfortable diaper. When applying a diaper to a baby the diaper is laid out flat and the baby is sat on it approximately in the center. In this way, the rear portion can be folded up onto the baby's back and the front portion can be folded up onto the baby's belly.
Obviously this can also be done with the baby lying down. The back right and left corners of the diaper are typically attached to the front of the diaper so as to form a circular waist closure. This closure is typically facilitated by providing the back part of the diaper with attachment tapes extending from the right and left longitudinal edges. Upon closure, these tapes can be connected to a landing zone on the front of the diaper. An attachment portion of the tapes provides a releasable attachment to the landing zone.
If the closure system is adhesive, the landing zone should provide the possibility to unfasten the tapes and replace them for a better fit or for better control of the diaper. Because skin treatment aids such as cream or powders are often used in diapering, adhesive tapes have been found to be less advantageous than mechanical interlocking devices. Such mechanical devices allow closure even if contaminated with a minor quantity of cream and powder. Some mechanical interlocking systems are limited by an inability to adjust the specific location where the attachment is made. Hence the flexibility of adhesive tape closure systems and the resistance to contamination of mechanical closure systems have been combined in the so-called hook and loop fastener systems, sometimes also referred to by their trade name as Velcro™. Typically, in such closures the hook elements are provided on the tapes and the loop elements are provided in the landing zone.
These conventional systems essentially consist of a tape joined to the diaper along its longitudinal edges in the rear portion of the diaper. Such joining is usually relatively close to the rear end of the diaper. These tapes comprise hook elements capable of engaging mechanically with loops. Typically, prior to use the tapes extending outwardly from the longitudinal side edge of the diaper are folded along the longitudinal side edge of the diaper to protect the hook elements. In this condition the hook material is protected between the tape material and the inner surface of the diaper. The tapes can be held in this folded position either by adhesive means (which must be protected so as to insure that the adhesive is not exposed to the skin of the baby during use) or by mechanical engaging between the hook material itself and the inner surface of the diaper. In this latter case, the inner surface is made of a material capable of at least temporary mechanical interaction with the hooks. Many non-woven materials used for the inner surface of a diaper provide this functionality without the need for any particular manipulation. Another means of holding the tapes in this folded position is, for example, crimping.
Upon opening, the tapes have to be grabbed by the person applying the diaper to a baby. For this reason, tapes usually have a finger-tab. The finger-tab has to be optimized to provide sufficient space to be grabbed. Since not all babies like to be diapered and sometimes attempt to physically interfere with the diapering process, finger-tabs have to be easily found.
The mechanical hook fasteners have to be attached to a loop surface such that the hooks entangle with the loops and provide a sufficiently stable mechanical attachment, which resists primarily tangential forces and is not disrupted by conventional usage.
It is also important that during the closing of the diaper the landing zone is easily identifiable. This has been achieved conventionally by providing the landing zone with colors to highlight this zone relative to the surrounding diaper material. Such colors can be provided to the landing zone by any conventional methods such as printing. It also has been found that it is advantageous to provide a colored region with symmetry indicators, well known as fit-guides, with respect to the longitudinal centerline of the diaper. These indicators encourage symmetrical closure of the diaper around the waist of the baby.
It also is well known to those skilled in the art that the dimensions of the hooks and the loop-landing zone must be adjusted to each other. Apparently the landing zone must be at least as large as the hook elements on the tapes. Conventional diapers show that it is advantageous to have a landing zone which is somewhat larger in the longitudinal direction than the hook dimension in the longitudinal direction. This ensures complete engagement between the two closure system portions in the longitudinal direction. The landing zone dimension in the transverse direction is selected such that it allows free placement of the hooks to adjust the diaper circumference around the baby's waist to fit comfortably. Most usually this requires a landing zone dimension in the transverse direction of about the same as the diaper width at the front end of the diaper.
In other prior art embodiments, there is a visual aide to help a user place the hook elements of the tapes on center in the longitudinal dimension of the landing zone. This is achieved by coloring the central portion in the longitudinal direction of the landing zone and by providing a boundary portion beyond the edges of the central portion in a color which blends into the surrounding diaper material. (Typically, a white boundary can be used on a white diaper backsheet. Even more conveniently, a transparent boundary can naturally provide the same color as the backsheet). In this way, the diapering person tries to place the mechanical tape into the colored central portion. However, the person is not penalized by reduced closure performance if the placement in the central portion is not exactly met. Also known are fit guides in the landing zone to indicate a transverse distance from the tape placement to the longitudinal centerline. These guides ensure symmetrical closure of the diaper on the right and left side. For such transverse fit guides, a centrally colored landing zone with a boundary zone can be considered a centralizing closure aide in the longitudinal direction.
For even better diaper fit and comfort, tapes for diapers have been provided with elasticity. Economically, such tapes are significantly less attractive due to exorbitant material costs and consumption. Such elastic tapes have drawbacks, such as pivoting or rotating around the elastically extensible portion of the tape. Of course the same issue becomes apparent for non-elastic tapes if their longitudinal dimension is too small, i.e. if their size approaches a narrow band. In order to address this issue on non-elastic tapes a so called y-bond tape attachment has been developed. For a y-bond tape attachment, the attachment portion of the tape on the diaper is sandwiched around the diaper longitudinal edge and extended for a few millimeters beyond this edge. This reinforces the extending portion of the tape to suppress the tape rotating or pivoting effect. In elasticized tapes this problem has been addressed by providing such tapes with a significantly larger longitudinal dimension (usually without a y-bond). This adds further to the structural cost disadvantage of elasticized tapes over non-elastic tapes. Of course, elastically extensible tapes have been used as they provide a permanent adjustment of the force in a circumferential path around the waist of a baby, thereby providing a beneficial fit. It is, however, also well established in the art that this adjustment can be provided in the end regions of a diaper. It is often provided by an elasticized waistband portion (as is conventional in the textile industry for undergarments).